The board doesn't have the authority to close Mirant either  the gas and diesel power plant operates with a Reliability-Must-Run contract and the state's grid operator, California Independent System Operator (Cal-ISO), has said Mirant must run or be replaced by some other in-city, instantly available power generation.

The plant also operates with a water permit from the Regional Water Quality Control Board, and though City Attorney Dennis Herrera, Maxwell, and Peskin recently sent a letter urging no renewal of the permit, which expires Dec. 31, the water board seems to be waiting for the plant to close by some other means rather than taking up the issue. "I'm currently reworking the permit reissuance schedule without Potrero because Potrero's status is really more like 'to be determined' at this point," wrote water board staff member Bill Johnson in an e-mail to the Guardian. Because the board hasn't acted on it, the permit will automatically be extended on Jan. 1, 2009, meaning the plant will be operating indefinitely until the water board makes a final decision or some other way to close it is found.

There's almost unanimous approval throughout the city that beefing up transmission lines would be better than building a power plant or allowing Mirant to keep operating. Transmission is also one way the city could gain more control of energy resources and potentially save, and even make, some money.

On Dec. 15, Barbara Hale, assistant general manager for power, sent a request to Cal-ISO asking that two new SFPUC transmission proposals be considered as part of the state's regional planning. They include upping the voltage of existing lines between the Hetch Hetchy dam and Newark, and adding a new line between Newark and Treasure Island, which would allow Hetch Hetchy power to travel exclusively on city-owned lines. The city currently pays PG&E $4 million per year to carry Hetch Hetchy power from Newark into the city  a fee San Francisco has been paying since 1925 when the city, during construction of the transmission lines between Yosemite and the Bay, mysteriously ran out of copper wire just a few miles shy of PG&E's Newark station.

The new line would run under the bay, using an existing SFPUC water pipeline right-of-way. "This pathway will allow transmission lines to traverse the environmentally sensitive Don Edwards Regional Wildlife Preserve [in Newark] that is likely to be a bottleneck between PG&E's pivotal Newark substation and the substation serving the Peninsula," the letter states. The SFPUC also predicts some possible cost recovery from Cal-ISO for building the Newark line because it would improve regional reliability. The agency also says it's exploring partnerships with other municipal utilities for joint ownership.